A medical device can be configured to sense an intrinsic electrical signal in the heart and to deliver therapy to the heart. Cardiac stimulation therapies include both low energy therapies and high-energy therapies. Low energy therapies include, for example, cardioversion, anti-tachycardia pacing (ATP) and other types of cardiac resynchronization therapy (CRT). Low energy therapies typically involve sending a low-voltage signal through one or more conductors. High energy therapies such as defibrillation typically involve sending a high-voltage signal through one or more conductors to the heart.
Cardiac sensing and cardiac stimulation usually involve transmitting an electric signal through a conductor that is part of a lead assembly. A lead assembly typically includes an insulative tube and conductors extending through the tube. Improved lead assemblies are needed.